Electrical feedthrough assemblies provide a conductive path extending between the interior of a hermetically sealed container and a point outside the container. Some implantable medical device components such as biorhythm sensors, pressure sensors, and pulse generators are contained as such and incorporate feedthrough assemblies. The conductive path comprises a conductive pin or terminal that is electrically insulated from the container. Many feedthrough assemblies, which are known in the art, include the terminal, a ferrule surrounding the terminal, an insulating body such as a glass or ceramic material for positioning and insulating the pin within the ferrule, and an epoxy backfill of the ferrule, over the insulator and around the terminal.
Feedthrough corrosion may be encountered with any medical device components possessing a terminal that comes into contact with body fluids or electrolytes, if fluid leak paths form in the backfill or at the interface of the backfill with the terminal and or ferrule. Furthermore, loading of the feedthrough under a constant DC bias in the presence of moisture and contamination or electrolyte can accelerate corrosion and the formation of dendrites. A build up of corrosion by-products within the feedthrough can also result in additional stresses, which may form cracks within the insulator. Accordingly, it is desirable to provide a more durable feedthrough backfill for medical device components, which is not susceptible to formation of fluid leak paths.